In the related art, in video cameras, digital still cameras, or the like, solid-state imaging devices including a CCD (Charge Coupled Device) or a CMOS image sensor are widely used. In these solid-state imaging devices, a light receiving section including photodiode is provided for each pixel, and in the light receiving section, incident light is photoelectrically converted and thereby a signal charge is generated.
In a CCD-type solid-state imaging device, the signal charge generated in the light receiving section is transferred to a charge transferring section having a CCD structure, and is converted into a pixel signal in an output section and then is output. On the other hand, in a CMOS-type solid-state imaging devices, the signal charge generated in the light receiving section is amplified for each pixel, and the amplified signal is output as a pixel signal by a signal line.
In such a solid-state imaging device, there is a problem in that aliasing occurs inside a semiconductor substrate due to inclined incident light or incident light that is diffusely reflected at an upper portion of the light receiving section, and thereby optical noise such as smearing and flaring occurs.
Therefore, in JP-A-2004-140152, in regard to the CCD-type solid-state imaging device, there is disclosed a technology for suppressing the occurrence of smearing by forming a light shielding film provided at an upper portion of the charge transferring section in a manner to be embedded in a groove portion formed in the interface of the light receiving section and a read-out gate section. However, in the technology disclosed in JP-A-2004-140152, since the light shielding film is formed in the groove portion formed by using a LOCOS oxide film, it is difficult to form the light shielding film at a deep portion of the substrate, and thereby it is difficult to reliably prevent the inclined incident light, which is a cause of smearing, from being incident. In addition, since the pixel area is diminished in proportion to the embedding depth of the light shielding film, it is basically difficult to deeply embed the light shielding film.
However, in recent years, accompanying the miniaturization and lowering of power consumption of a video camera or a digital still camera, and a mobile phone with camera, the CMOS-type solid-state imaging device is frequently used. In addition, as the CMOS-type solid-state imaging device, a front-surface irradiation type shown in FIG. 24 and a rear-surface irradiation type shown in FIG. 25 are known.
As shown in a schematic configuration diagram of FIG. 24, a front-surface irradiation type solid-state imaging device 111 is configured to have a pixel region 113 in which a plurality of unit pixels 116 including a photodiode PD serving as a photoelectric conversion section and a plurality of pixel transistors is formed in a semiconductor substrate 112. Although the pixel transistor is not shown, a gate electrode 114 is shown in FIG. 24 and this indicates schematically the presence of the pixel transistor.
Each photodiode PD is separated by a device separating region 115 composed of an impurity diffused layer, and a multi-layered interconnection layer 119 where a plurality of interconnections 118 are disposed via an interlayer insulating film 117 are formed on a front-surface side of the semiconductor substrate 112 where the pixel transistor is formed. The interconnection 118 is formed except for a portion corresponding to the location of the photodiode PD.
An on-chip color filter 121 and an on-chip microlens 122 are sequentially formed on the multi-layered interconnection layer 119 via a planarized film 120. The on-chip color filter 121 is configured by arranging each color filter of, for example, red (R), green (G), and blue (B).
In the front-surface irradiation type solid-state imaging device 111, a front surface of a substrate where the multi-layered interconnection layer 119 is formed is set as a light receiving plane 123, and light L is incident from the front surface side of the substrate.
On the other hand, as shown in a schematic configuration diagram of FIG. 25, a rear-surface irradiation type solid-state imaging device 131 is configured to have the pixel region 113 in which a plurality of unit pixels 116 including a photodiode PD serving as a photoelectric conversion section and a plurality of pixel transistors are formed in the semiconductor substrate 112. Although not shown, the pixel transistor is formed in the substrate front-surface side, and the gate electrode 114 is shown in FIG. 25 and this indicates schematically the presence of the pixel transistor.
Each photodiode PD is separated by the device separating region 115 composed of an impurity diffused layer, and the multi-layered interconnection layer 119 where a plurality of interconnections 118 are disposed via the interlayer insulating film 117 is formed on a front-surface side of the semiconductor substrate 112 where the pixel transistor is formed. In the rear-surface irradiation type, the interconnection 118 may be formed regardless of the position of the photodiode PD.
In addition, on a rear surface that the photodiode PD of the semiconductor substrate 112 faces, an insulating layer 128, the on-chip color filter 121, and on-chip microlens 122 are sequentially formed.
In the rear-surface irradiation type solid-state imaging device 131, the rear surface of the substrate, which is opposite to the substrate front-surface side where the multi-layered interconnection layer and the pixel transistor are formed, is set as a light receiving plane 132, and light L may be incident from the rear surface-side of the substrate.
Increasing integration of a device through the miniaturization of the pixels has been demanded. However, the front-surface irradiation type solid-state imaging device 111 has a configuration where the light L is received by the photodiode PD through the multi-layered interconnection layer 119. Therefore, accompanying the progress of increasing integration and the miniaturization of the pixels, there is a problem in that it is difficult to sufficiently secure a light receiving section region due to an obstacle such as the interconnection, and thereby sensitivity is decreased or shading increases.
On the other hand, in the rear-surface irradiation type solid-state imaging device 131, the light L can be incident to the photodiode PD without being subjected to a restriction due to the multi-layered interconnection layer 119, such that it is possible to broaden the opening of the photodiode PD and thereby it is possible to realize increased sensitivity.